The present invention is related to adjustable anchors for cables bearing civil engineering structures, to civil engineering structures including such anchors, and to methods for adjusting such anchors.
Adjusting the length and/or tension of civil engineering structure cables, for example of suspension bridge hangers or possibly guys, is generally a complex operation and tricky to implement.
The purpose of the present invention is therefore to propose an anchor for a civil engineering structure suspension cable that enables such an adjustment to be made simply, economically and safely.
For this purpose, according to the invention, an adjustable anchor for a cable bearing a civil engineering structure comprises:
a first anchoring part designed to be fixed to the cable and including a first thread centered on a longitudinal axis,
a second anchoring part fitted, with some play along said longitudinal axis, onto a support designed to be fixed to the civil engineering structure, the second anchoring part including a second thread in the reverse direction to the first thread, said second thread being centered on said longitudinal axis and arranged toward the first thread,
and a linking part including first and second threaded ends complementary to the first and second threads and co-operating by screwing (preferably with play, but not necessarily) with these.
Thanks to these arrangements, the length and/or tension of the cable can easily be adjusted:
by bringing the first anchoring part and the support closer to one another at least partially by means of an adjustment device,
then by turning the linking part so as to screw it or unscrew it in relation to both anchoring parts, which brings the two anchoring parts closer together or farther apart from one another and therefore produces an effect equivalent to a shortening or to a lengthening of the cable.
To shorten the cable, one generally begins by substantially taking up all the play between the first anchoring part and the support in order then to be able to move the second anchoring part toward said second anchoring part, while to lengthen the cable, one generally begins by moving the second anchoring part very slightly toward the support so as then to be able to move the first anchoring part toward said support by unscrewing the linking part.
It will be noted that during this adjustment, the first and second anchoring parts are never uncoupled from the support, which confers great safety in use upon the adjustable anchor according to the invention.
In preferred embodiments of the invention, recourse may further be made to one and/or another of the following arrangements:
the play between the second anchoring part and the support is greater than 3 mm along the longitudinal axis;
the second anchoring part is a clevis that comprises two flanges arranged on either side of the support, the two flanges and the support being traversed by a pin perpendicular to the longitudinal axis, play being allowed between the pin and at least one element chosen from the clevis and the support;
the two flanges of the clevis have oblong holes respectively arranged in mutual correspondence in such a way as to create the play between the pin and the clevis;
the support further includes a mounting hole perpendicular to the longitudinal axis, which is arranged beyond the flanges of the clevis and which is adapted to receive an additional temporary pin: this additional pin is thus used as the engagement point of the adjustment tool designed to bring the first anchoring part at least partially closer to the support.
Moreover, the object of the invention is also a civil engineering structure comprising a suspended part that is connected to at least a cable via an adjustable anchor as defined above.
Finally, the object of the invention is also a method for adjusting an anchor such as that defined above by means of an adjustment tool including first and second parts and activation means for bringing them closer to one another, this method comprising the following steps:
fixing the first part of the adjustment tool to the first anchoring part,
fixing the second part of the adjustment tool to an integral element of the support,
bringing the first anchoring part of said support closer in order to take up the play at least partially between the second anchoring part and said support,
and turning the linking part around the longitudinal axis so as to adjust the distance between the first and second anchoring parts to a desired value.
Advantageously, the second part of the adjustment tool can be fixed to a pin engaged in a mounting hole of the support perpendicularly to the longitudinal axis, or to a pin that traverses both the second anchoring part and the support perpendicularly to the longitudinal axis.